Additive (+) and Subtractive (-) Synthesis

Sounds can be added together or subtracted from one another. Learn how new sounds can be made in this way.

Additive Synthesis

Additive Synthesis involves building complex sounds from simple components (adding them together). As we saw in Complex Soundwaves, sounds can be added together to make new and more complex sounds. The most pure and basic type of sound is a sine wave. But if we analyse more complex sounds we can observe that complex sounds are often made up of multiple sine waves.

One individual sine wave, which forms the basis of a guitar pluck sound

Listening Challenge

Listen to the individual sine wave component on its own and then play the original guitar sound. Can you hear the individual sine wave as part of the original guitar sound? Listening to the sine wave on its own draws our ears attention to it and allows us to pick out this specific tone within the more complex sound of the original guitar pluck.

Activity

Start with a collection of simple sine wave sounds and use these to build more complex sounds, using the process of additive synthesis.

Subtractive Synthesis

Subtractive synthesis involves carving sounds out of complex sounds or Noise (taking sound energy away from a busy / noisy source). Noise sounds contain a randomised assortment of sound energy spread across the sound spectrum. By using filters we can carve sounds out of noise, much like a sculptor might carve a statue out of a block of marble.